1. Field of the Invention
The present invention relates to a nonlinear semiconductor element having a diode characteristic and a liquid crystal display panel employing the same. The invention also pertains to methods for the manufacture of the nonlinear semiconductor element and the liquid crystal display panel.
2. Description of the Prior Art
Heretofore there has been proposed a display panel which employs m.times.n (where n.gtoreq.1 and m.gtoreq.1) liquid crystal display devices D.sub.11 to D.sub.1n, D.sub.21 to D.sub.2n, . . . and D.sub.m1 to D.sub.mn.
In this display panel, a liquid crystal element C.sub.ij (where i=1, 2 . . . m; j=1, 2 . . . n) is connected via a nonlinear element H.sub.ij to a row line x.sub.i and a column line Y.sub.j at their intersection.
With such a display panel, an image display can be provided by driving the liquid crystal elements at the intersections of selected ones of row lines x.sub.1 to x.sub.m and column lines Y.sub.1 to Y.sub.n through the selected lines.
The conventional display panel employs, as the nonlinear element H.sub.ij, insulated gate FET or n-i-n, n-i-p(or p-)-i-p type nonlinear semiconductor element.
The manufacture of the insulated gate FET calls for many steps using as many as six to eight photo masks. Accordingly, the conventional display panel employing the insulated gate FETs as the nonlinear elements cannot be fabricated with high production yield, with ease and at low cost.
The nonlinear semiconductor element, as the nonlinear element H.sub.ij, is easier to fabricate at lower cost than the insulated gate FET. But the V-I (voltage-current) characteristics of the conventional nonlinear element is poor in origin symmetry. On account of this, in the case of driving the liquid crystal element by AC (alternative current) power via the nonlinear element, transparency or nontransparency of the liquid crystal element differs during the positive half cycle and during the negative cycle of the AC power, flickering a display by the liquid crystal element.
Furthermore, the conventional nonlinear semiconductor element has such a V-I characteristic that current at the time of voltage being zero has a relatively large value which cannot be neglected. That is to say, the nonlinear semiconductor element is accompanied by an appreciable amount of leakage current. Accordingly, even when the liquid crystal element is not driven (i.e. in the case where the power source is connected to the liquid crystal element but the power source voltage is zero) the leakage current is charged in the liquid crystal element, making it transparency or nontransparency lower though slightly than in the case of the power source being disconnected.